Enable detekt rules `UseLet` and fix existing issues.

libraries/matrixui/src/main/kotlin/io/element/android/libraries/matrix/ui/room/MatrixRoomMembers.kt

@@ -57,14 +57,9 @@ fun MatrixRoom.getDirectRoomMember(roomMembersState: MatrixRoomMembersState): St
     val roomMembers = roomMembersState.roomMembers()
     return remember(roomMembersState) {
         derivedStateOf {
-            if (roomMembers == null) {
-                null
-            } else if (roomMembers.size == 2 && isDirect && isEncrypted) {
-                roomMembers.find { it.userId != this.sessionId }
-            } else {
-                null
-            }
+            roomMembers
+                ?.takeIf { it.size == 2 && isDirect && isEncrypted }
+                ?.find { it.userId != sessionId }
         }
     }
 }
-

libraries/push/impl/src/main/kotlin/io/element/android/libraries/push/impl/push/DefaultPushHandler.kt

@@ -100,15 +100,15 @@ class DefaultPushHandler @Inject constructor(
             }
 
             val clientSecret = pushData.clientSecret
-            val userId = if (clientSecret == null) {
-                // Should not happen. In this case, restore default session
-                null
-            } else {
-                // Get userId from client secret
-                pushClientSecret.getUserIdFromSecret(clientSecret)
-            } ?: run {
-                matrixAuthenticationService.getLatestSessionId()
-            }
+            // clientSecret should not be null. If this happens, restore default session
+            val userId = clientSecret
+                ?.let {
+                    // Get userId from client secret
+                    pushClientSecret.getUserIdFromSecret(clientSecret)
+                }
+                ?: run {
+                    matrixAuthenticationService.getLatestSessionId()
+                }
 
             if (userId == null) {
                 Timber.w("Unable to get a session")

tools/detekt/detekt.yml

@@ -63,6 +63,8 @@ style:
   UseDataClass:
     active: true
     allowVars: false
+  UseLet:
+    active: true
 
 coroutines:
   GlobalCoroutineUsage: